1 files changed, 79 insertions, 69 deletions

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 63e5b90da1f3..a723b7dc6e4e 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -95,6 +95,9 @@ EXPORT_SYMBOL_GPL(cgroup_mutex);
 EXPORT_SYMBOL_GPL(css_set_lock);
 #endif
 
+struct blocking_notifier_head cgroup_lifetime_notifier =
+	BLOCKING_NOTIFIER_INIT(cgroup_lifetime_notifier);
+
 DEFINE_SPINLOCK(trace_cgroup_path_lock);
 char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
 static bool cgroup_debug __read_mostly;
@@ -161,10 +164,14 @@ static struct static_key_true *cgroup_subsys_on_dfl_key[] = {
 };
 #undef SUBSYS
 
-static DEFINE_PER_CPU(struct cgroup_rstat_cpu, cgrp_dfl_root_rstat_cpu);
+static DEFINE_PER_CPU(struct css_rstat_cpu, root_rstat_cpu);
+static DEFINE_PER_CPU(struct cgroup_rstat_base_cpu, root_rstat_base_cpu);
 
 /* the default hierarchy */
-struct cgroup_root cgrp_dfl_root = { .cgrp.rstat_cpu = &cgrp_dfl_root_rstat_cpu };
+struct cgroup_root cgrp_dfl_root = {
+	.cgrp.self.rstat_cpu = &root_rstat_cpu,
+	.cgrp.rstat_base_cpu = &root_rstat_base_cpu,
+};
 EXPORT_SYMBOL_GPL(cgrp_dfl_root);
 
 /*
@@ -1335,6 +1342,7 @@ static void cgroup_destroy_root(struct cgroup_root *root)
 {
 	struct cgroup *cgrp = &root->cgrp;
 	struct cgrp_cset_link *link, *tmp_link;
+	int ret;
 
 	trace_cgroup_destroy_root(root);
 
@@ -1343,6 +1351,10 @@ static void cgroup_destroy_root(struct cgroup_root *root)
 	BUG_ON(atomic_read(&root->nr_cgrps));
 	BUG_ON(!list_empty(&cgrp->self.children));
 
+	ret = blocking_notifier_call_chain(&cgroup_lifetime_notifier,
+					   CGROUP_LIFETIME_OFFLINE, cgrp);
+	WARN_ON_ONCE(notifier_to_errno(ret));
+
 	/* Rebind all subsystems back to the default hierarchy */
 	WARN_ON(rebind_subsystems(&cgrp_dfl_root, root->subsys_mask));
 
@@ -1371,7 +1383,6 @@ static void cgroup_destroy_root(struct cgroup_root *root)
 
 	cgroup_unlock();
 
-	cgroup_rstat_exit(cgrp);
 	kernfs_destroy_root(root->kf_root);
 	cgroup_free_root(root);
 }
@@ -1715,7 +1726,7 @@ static void css_clear_dir(struct cgroup_subsys_state *css)
 
 	css->flags &= ~CSS_VISIBLE;
 
-	if (!css->ss) {
+	if (css_is_self(css)) {
 		if (cgroup_on_dfl(cgrp)) {
 			cgroup_addrm_files(css, cgrp,
 					   cgroup_base_files, false);
@@ -1747,7 +1758,7 @@ static int css_populate_dir(struct cgroup_subsys_state *css)
 	if (css->flags & CSS_VISIBLE)
 		return 0;
 
-	if (!css->ss) {
+	if (css_is_self(css)) {
 		if (cgroup_on_dfl(cgrp)) {
 			ret = cgroup_addrm_files(css, cgrp,
 						 cgroup_base_files, true);
@@ -1876,13 +1887,6 @@ int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
 		}
 		spin_unlock_irq(&css_set_lock);
 
-		if (ss->css_rstat_flush) {
-			list_del_rcu(&css->rstat_css_node);
-			synchronize_rcu();
-			list_add_rcu(&css->rstat_css_node,
-				     &dcgrp->rstat_css_list);
-		}
-
 		/* default hierarchy doesn't enable controllers by default */
 		dst_root->subsys_mask |= 1 << ssid;
 		if (dst_root == &cgrp_dfl_root) {
@@ -2065,7 +2069,6 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
 	cgrp->dom_cgrp = cgrp;
 	cgrp->max_descendants = INT_MAX;
 	cgrp->max_depth = INT_MAX;
-	INIT_LIST_HEAD(&cgrp->rstat_css_list);
 	prev_cputime_init(&cgrp->prev_cputime);
 
 	for_each_subsys(ss, ssid)
@@ -2146,7 +2149,7 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 	if (ret)
 		goto destroy_root;
 
-	ret = cgroup_rstat_init(root_cgrp);
+	ret = css_rstat_init(&root_cgrp->self);
 	if (ret)
 		goto destroy_root;
 
@@ -2154,10 +2157,9 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 	if (ret)
 		goto exit_stats;
 
-	if (root == &cgrp_dfl_root) {
-		ret = cgroup_bpf_inherit(root_cgrp);
-		WARN_ON_ONCE(ret);
-	}
+	ret = blocking_notifier_call_chain(&cgroup_lifetime_notifier,
+					   CGROUP_LIFETIME_ONLINE, root_cgrp);
+	WARN_ON_ONCE(notifier_to_errno(ret));
 
 	trace_cgroup_setup_root(root);
 
@@ -2188,7 +2190,7 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 	goto out;
 
 exit_stats:
-	cgroup_rstat_exit(root_cgrp);
+	css_rstat_exit(&root_cgrp->self);
 destroy_root:
 	kernfs_destroy_root(root->kf_root);
 	root->kf_root = NULL;
@@ -5444,8 +5446,9 @@ static void css_free_rwork_fn(struct work_struct *work)
 	struct cgroup *cgrp = css->cgroup;
 
 	percpu_ref_exit(&css->refcnt);
+	css_rstat_exit(css);
 
-	if (ss) {
+	if (!css_is_self(css)) {
 		/* css free path */
 		struct cgroup_subsys_state *parent = css->parent;
 		int id = css->id;
@@ -5474,7 +5477,6 @@ static void css_free_rwork_fn(struct work_struct *work)
 			cgroup_put(cgroup_parent(cgrp));
 			kernfs_put(cgrp->kn);
 			psi_cgroup_free(cgrp);
-			cgroup_rstat_exit(cgrp);
 			kfree(cgrp);
 		} else {
 			/*
@@ -5499,14 +5501,10 @@ static void css_release_work_fn(struct work_struct *work)
 	css->flags |= CSS_RELEASED;
 	list_del_rcu(&css->sibling);
 
-	if (ss) {
+	if (!css_is_self(css)) {
 		struct cgroup *parent_cgrp;
 
-		/* css release path */
-		if (!list_empty(&css->rstat_css_node)) {
-			cgroup_rstat_flush(cgrp);
-			list_del_rcu(&css->rstat_css_node);
-		}
+		css_rstat_flush(css);
 
 		cgroup_idr_replace(&ss->css_idr, NULL, css->id);
 		if (ss->css_released)
@@ -5532,7 +5530,7 @@ static void css_release_work_fn(struct work_struct *work)
 		/* cgroup release path */
 		TRACE_CGROUP_PATH(release, cgrp);
 
-		cgroup_rstat_flush(cgrp);
+		css_rstat_flush(&cgrp->self);
 
 		spin_lock_irq(&css_set_lock);
 		for (tcgrp = cgroup_parent(cgrp); tcgrp;
@@ -5580,7 +5578,6 @@ static void init_and_link_css(struct cgroup_subsys_state *css,
 	css->id = -1;
 	INIT_LIST_HEAD(&css->sibling);
 	INIT_LIST_HEAD(&css->children);
-	INIT_LIST_HEAD(&css->rstat_css_node);
 	css->serial_nr = css_serial_nr_next++;
 	atomic_set(&css->online_cnt, 0);
 
@@ -5589,9 +5586,6 @@ static void init_and_link_css(struct cgroup_subsys_state *css,
 		css_get(css->parent);
 	}
 
-	if (ss->css_rstat_flush)
-		list_add_rcu(&css->rstat_css_node, &cgrp->rstat_css_list);
-
 	BUG_ON(cgroup_css(cgrp, ss));
 }
 
@@ -5684,6 +5678,10 @@ static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
 		goto err_free_css;
 	css->id = err;
 
+	err = css_rstat_init(css);
+	if (err)
+		goto err_free_css;
+
 	/* @css is ready to be brought online now, make it visible */
 	list_add_tail_rcu(&css->sibling, &parent_css->children);
 	cgroup_idr_replace(&ss->css_idr, css, css->id);
@@ -5697,7 +5695,6 @@ static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
 err_list_del:
 	list_del_rcu(&css->sibling);
 err_free_css:
-	list_del_rcu(&css->rstat_css_node);
 	INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
 	queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
 	return ERR_PTR(err);
@@ -5713,7 +5710,7 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
 	struct cgroup_root *root = parent->root;
 	struct cgroup *cgrp, *tcgrp;
 	struct kernfs_node *kn;
-	int level = parent->level + 1;
+	int i, level = parent->level + 1;
 	int ret;
 
 	/* allocate the cgroup and its ID, 0 is reserved for the root */
@@ -5725,17 +5722,13 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
 	if (ret)
 		goto out_free_cgrp;
 
-	ret = cgroup_rstat_init(cgrp);
-	if (ret)
-		goto out_cancel_ref;
-
 	/* create the directory */
 	kn = kernfs_create_dir_ns(parent->kn, name, mode,
 				  current_fsuid(), current_fsgid(),
 				  cgrp, NULL);
 	if (IS_ERR(kn)) {
 		ret = PTR_ERR(kn);
-		goto out_stat_exit;
+		goto out_cancel_ref;
 	}
 	cgrp->kn = kn;
 
@@ -5745,15 +5738,20 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
 	cgrp->root = root;
 	cgrp->level = level;
 
-	ret = psi_cgroup_alloc(cgrp);
+	/*
+	 * Now that init_cgroup_housekeeping() has been called and cgrp->self
+	 * is setup, it is safe to perform rstat initialization on it.
+	 */
+	ret = css_rstat_init(&cgrp->self);
 	if (ret)
 		goto out_kernfs_remove;
 
-	if (cgrp->root == &cgrp_dfl_root) {
-		ret = cgroup_bpf_inherit(cgrp);
-		if (ret)
-			goto out_psi_free;
-	}
+	ret = psi_cgroup_alloc(cgrp);
+	if (ret)
+		goto out_stat_exit;
+
+	for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp))
+		cgrp->ancestors[tcgrp->level] = tcgrp;
 
 	/*
 	 * New cgroup inherits effective freeze counter, and
@@ -5771,24 +5769,6 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
 		set_bit(CGRP_FROZEN, &cgrp->flags);
 	}
 
-	spin_lock_irq(&css_set_lock);
-	for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) {
-		cgrp->ancestors[tcgrp->level] = tcgrp;
-
-		if (tcgrp != cgrp) {
-			tcgrp->nr_descendants++;
-
-			/*
-			 * If the new cgroup is frozen, all ancestor cgroups
-			 * get a new frozen descendant, but their state can't
-			 * change because of this.
-			 */
-			if (cgrp->freezer.e_freeze)
-				tcgrp->freezer.nr_frozen_descendants++;
-		}
-	}
-	spin_unlock_irq(&css_set_lock);
-
 	if (notify_on_release(parent))
 		set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
 
@@ -5797,7 +5777,29 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
 
 	cgrp->self.serial_nr = css_serial_nr_next++;
 
+	ret = blocking_notifier_call_chain_robust(&cgroup_lifetime_notifier,
+						  CGROUP_LIFETIME_ONLINE,
+						  CGROUP_LIFETIME_OFFLINE, cgrp);
+	ret = notifier_to_errno(ret);
+	if (ret)
+		goto out_psi_free;
+
 	/* allocation complete, commit to creation */
+	spin_lock_irq(&css_set_lock);
+	for (i = 0; i < level; i++) {
+		tcgrp = cgrp->ancestors[i];
+		tcgrp->nr_descendants++;
+
+		/*
+		 * If the new cgroup is frozen, all ancestor cgroups get a new
+		 * frozen descendant, but their state can't change because of
+		 * this.
+		 */
+		if (cgrp->freezer.e_freeze)
+			tcgrp->freezer.nr_frozen_descendants++;
+	}
+	spin_unlock_irq(&css_set_lock);
+
 	list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children);
 	atomic_inc(&root->nr_cgrps);
 	cgroup_get_live(parent);
@@ -5815,10 +5817,10 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
 
 out_psi_free:
 	psi_cgroup_free(cgrp);
+out_stat_exit:
+	css_rstat_exit(&cgrp->self);
 out_kernfs_remove:
 	kernfs_remove(cgrp->kn);
-out_stat_exit:
-	cgroup_rstat_exit(cgrp);
 out_cancel_ref:
 	percpu_ref_exit(&cgrp->self.refcnt);
 out_free_cgrp:
@@ -6015,7 +6017,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
 	struct cgroup *tcgrp, *parent = cgroup_parent(cgrp);
 	struct cgroup_subsys_state *css;
 	struct cgrp_cset_link *link;
-	int ssid;
+	int ssid, ret;
 
 	lockdep_assert_held(&cgroup_mutex);
 
@@ -6073,8 +6075,9 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
 
 	cgroup1_check_for_release(parent);
 
-	if (cgrp->root == &cgrp_dfl_root)
-		cgroup_bpf_offline(cgrp);
+	ret = blocking_notifier_call_chain(&cgroup_lifetime_notifier,
+					   CGROUP_LIFETIME_OFFLINE, cgrp);
+	WARN_ON_ONCE(notifier_to_errno(ret));
 
 	/* put the base reference */
 	percpu_ref_kill(&cgrp->self.refcnt);
@@ -6136,6 +6139,9 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
 	} else {
 		css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL);
 		BUG_ON(css->id < 0);
+
+		BUG_ON(ss_rstat_init(ss));
+		BUG_ON(css_rstat_init(css));
 	}
 
 	/* Update the init_css_set to contain a subsys
@@ -6184,6 +6190,8 @@ int __init cgroup_init_early(void)
 		     ss->id, ss->name);
 		WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
 		     "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
+		WARN(ss->early_init && ss->css_rstat_flush,
+		     "cgroup rstat cannot be used with early init subsystem\n");
 
 		ss->id = i;
 		ss->name = cgroup_subsys_name[i];
@@ -6212,7 +6220,7 @@ int __init cgroup_init(void)
 	BUG_ON(cgroup_init_cftypes(NULL, cgroup_psi_files));
 	BUG_ON(cgroup_init_cftypes(NULL, cgroup1_base_files));
 
-	cgroup_rstat_boot();
+	BUG_ON(ss_rstat_init(NULL));
 
 	get_user_ns(init_cgroup_ns.user_ns);
 
@@ -6225,6 +6233,8 @@ int __init cgroup_init(void)
 	hash_add(css_set_table, &init_css_set.hlist,
 		 css_set_hash(init_css_set.subsys));
 
+	cgroup_bpf_lifetime_notifier_init();
+
 	BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
 
 	cgroup_unlock();